Current of fast moving air in the upper levels of the atmosphere

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Jet Stream
Primary Points
Current of fast moving air in the upper levels of the atmosphere

In the US there is two Jet streams (Subtropical Jet and Polar Jet)

Polar jet is boundary between warm air mass and cold air mass

Jet streams are usually found between 10-15 km (6-9 miles) above Earth’s surface

Jet Streams can steer storms

Airplanes fly faster when traveling typically eastward on the Jet stream

Jet Streaks are the faster winds embedded into the Jet Stream

Stronger during the winter months because of the bigger temperature contrast

Jet stream shifts Northward during summer and Southward in the winter

Zonal pattern is a straighter jet stream while meridional contains more curves

Trivia and Stories
A volcano eruption helped discover the Jet stream

Used to be called the equatorial smoke stream

American pilot given some credit to discovering Jet stream

Flyers during World War II noticed tailwinds in excess of 100 mph during flights

Sound Bites
The sky’s River

Hop on the jet stream for a faster ride home

Sluggish Jetstream due to poor temperature contrast
Sources of Additional Info
Primary Points
Violent rotating column of air

Forms at the bottom of cumulonimbus cloud (thunderstorm)

Can be dangerous to life and property

Most tornadoes have wind speeds of less than 110 mile/hour

Extreme twisters can exceed 300 miles/hour

Types of tornadoes include waterspouts, dust devils, and fire whirl

In the US Tornado alley is where the mass majority of tornadoes occur

Tornadoes have been observed on every continent except Antarctica

Can have a wide range of colors depending on where the tornado develops

Lightning may not be present during a tornado

Trivia and Stories
Enhanced Fujita Scale was introduced in 2007 to assess damage more closely

Some people have seen inside tornadoes

Usually a tornado matches the color of the ground

US averages 1200 tornadoes every year

Sound Bites
Twisted up chaos after tornadoes tear through

Off the scale winds due to violent vortex

Sources of Additional Info


Primary Points
Measured using the Saffir-Simpson scale

Winds from hurricanes can be over 160 miles/hour

Atlantic’s Hurricane season peaks from mid-August to late October

Atlantic Ocean averages five to six hurricanes per year

Hurricanes are fed energy from the warm seas

90 percent of all hurricane deaths result from storm surges

Hurricanes can also spawn tornadoes

The eye of the hurricane is relatively calm

The strongest winds take place just outside the wall

Hurricanes weaken rapidly over land

Hurricanes forecasts are not as accurate for farther out tracks
Trivia and Stories
Hurricanes are also called Typhoons and Cyclones in other parts of the world

Medicanes (similar to hurricanes) for over the Mediterranean Sea

Hurricanes were first given names in the19th century by Clement Wragge

Hurricanes rotate clockwise in the southern Hemisphere

Sound Bites
Storm surge strikes coast from destructive Hurricane

Raging winds wait outside the eye.

Sources of Additional Info

Radar/Doppler Radar

Primary Points
Radar is used to detect precipitation in the atmosphere

Modern radars are pulse-Doppler Radars

Can be used to determine the structure of storms

Dual-Pol radar can detect shape and size of precipitation

Sends pulses of microwave radiation

Radar pulses spread out as they move away from the radar station

The duration of the “listening” cycle is about a millisecond long

Used in different modes to adjust to outside conditions. (Clear Air Mode)

Colors on radar is measured in reflectivity or dBZ
Trivia and Stories
There are also mobile Doppler radars (DOW)

Radars can detect insects, buildings, and birds

Radars have a velocity product, which can detect winds
Sound Bites
Rotating Radars show real results

Radar detects detailed hook echo to signify tornado

Sources of Additional Info

El Niño/La Niña

Primary Points
El Nino and La Nina are opposite phases of ENSO (El Nino-Southern Oscillation)

These phases take place in the east-central Equatorial Pacific

El Nino is the warm phase when water temperatures are warmer than average

La Nina is the cold phase when water temperatures are cooler than average

These phases typically last 9 to 12 months

Phases begin to form between June and August

Peak strength is reached between December/April and decay between May/July

ENSO phases occur every 3 to 5 years

North America weather conditions can be affected due to ENSO phases

Not associated with Global Warming

Trivia and Stories
El Nino means The Little Boy or Spanish Child in Spanish

Fishermen off of South America first recognized El Nino in the 1600s

La Nina means The Little Girl in Spanish

La Nina seasons usually mean a more active Hurricane Season

Sound Bites
Elusive El Nino arrives

It’s time to fire up the Super El Nino chatter again

La Nina conditions spin up springtime Twisters
Sources of Additional Info
Long-range Weather Prediction (Monthly, Seasonal)
Primary Points
Farmer’s Almanac is not a good way to look at long -range weather forecasts

The almanac is right less than half of the time

NOAA is a more reliable source to look at Long-Range Forecasts

NOAA uses Below Normal, Above Normal, Equal Chances for Long-Range

NOAA predicts Temperature and Precipitation for Long-Range

Monthly is more accurate due to it being closer in time

Long-Range is Much more inaccurate than Short-Range

Computer Models are used to create Long-Term Forecasts

Private Sector may create their own Long-Range forecasts
Trivia and Stories
Climatology is becoming more important for Long-Range

Many people rely on Farmer’s Almanac

Sound Bites
Rely on Long-range for reference

Meteorologists LOL at Long-range Almanac Forecasts

Sources of Additional Info


Primary Points
Occur in cumulonimbus clouds

Sometimes accompanied by strong winds, heavy rain, and hail

Thunderstorms may line up in a series or rain band known as a squall line

Thunderstorms may also rotate (Super cells)

Can produce tornadoes

Result from rapid upward movement of warm, moist air

Can occur inside warm, moist air masses or along fronts

Can form and develop in any particular geographic location

Threaten life and property

Damage from thunderstorms is mostly from hailstones, flash flooding, downbursts

Maximum daytime heating occurs at night allowing for convection
Trivia and Stories
A thunderstorm has enough energy to equal 50 A-Bombs (Hiroshima)

Sometimes thunderstorms can build large enough to go into the stratosphere

Can produce softball sized hail
Sound Bites
If thunder roars go indoors

Rumble of thunder find some cover

Sources of Additional Info

Climate Change

Primary Points
Change in the statistical distribution of weather patterns for an extended period

Referred to as global warming

El Nino does not represent climate change

Climate change is mainly caused from humans actions to pollute the atmosphere

Carbon Dioxide and Water vapor are the main causes of the warming Earth

General Circulation models used to link causes of climate change

Carbon Dioxide continues to increase

Every time you drive a car you are releasing carbon dioxide

The Greenhouse effect occurs when gases are trapped in the Earths Atmosphere

The melting of ice sheets is one thing climate change is affecting

Warmer global temperatures can actually bring more snow to the Northeast US

Ozone hole is formed from chlorine in the form of CFCs in the atmosphere

Trivia and Stories
Past couple winters were colder for eastern US not Western

Glaciers are most sensitive to Climate Change

Sound Bites
Climate Change Crippling America

Polar bears running out of room due to Climate Change

Sources of Additional Info

Winter Precipitation

Primary Points

Snow can fall above freezing temps because overlying air may be colder and the snow does not have enough time to melt when it reaches the ground

Snow, Sleet, Freezing Rain, Graupel is types of precipitation

Freezing rain can occur when the surface is below freezing and the air is above freezing

Wintry Precipitation can cause hazardous driving conditions

Snow can have different shapes and sizes

10 inches of snow is equivalent to 1 inch of rain

Snow can disappear with temperatures below freezing due to sublimation

Sublimation is the process when solid turn into a gas

Snow is the hardest to forecast

Snow requires a column of air that is at or below freezing
Trivia and Stories
No snowflake is the same

The largest snowflake was 15 inches wide

Sound Bites
Winter Whiteout

No winter lasts forever; no spring skips its turn

Mixed bag of precipitation
Sources of Additional Info

Primary Points

Only some folklore is true

Folklore began because back in the day there was no numerical data

Only instrument of reliability was human experience

Folklore refers to mid-latitude regions

Red sky at night sailors, delight; Red sky in the morning sailors take warning

Ring around sun or moon precipitation coming in

No weather is ill if the wind be still (False if there may be a calm before storm)

Groundhog is popular with folklore but is a false type of folklore

Decreasing pressure causes aches and pains and may signify storms on the way
Trivia and Stories
Many farmers used folklore to maintain their crops

Folklore may only be useful in certain seasons

Sound Bites
When sounds travel far and wide, a stormy day will betide

When clouds look like black smoke, A wise man will put on his cloak

Sources of Additional Info

Lake (Sea)-Effect Snow/Rain

Primary Points
Needs a warm lake, cold air, little shear, and location of where it falls depends on wind

Size of the bands depend on the shape of the body of water and prevailing wind

Snowfall may exceed 5 inches an hour

May not be snowing at all with clear skies a few miles away

Rain is also possible in spring and fall

Sea effect also occurs such as Cape Cod Bay and Chesapeake Bay

A band can stay in one location for several hours dropping several feet of snow

Snow bands can be 20 to 30 miles wide and extend 100 miles inland from lake

Ice cover stops or decreases snow activity

Ice cuts off the warm moist air needed to produce lake effect

Trivia and Stories
Thundersnow (Lightning in the snow) can occur with lake effect

Another area of extreme lake effect is in Japan

Sound Bites
Lake-effect bands make the skiers dance

Snow piles up due to Unrelenting Lake-Effect

Sources of Additional Info

Optical Phenomena

Primary Points
Observable events resulting from the interaction of light and matter

Rainbows form when there is sun and rain

Occurs when light is refracted by the water droplets

Rainbows can be seen in the snow as well

Sun dogs create a rainbow around the sun and also around the moon at times

Sun dogs are visible when sunlight is refracting off ice crystals high up in the atmosphere

Mirages occur when light rays are bent to produce a displaced image of distant objects

Light rays bend downward when entering layers of cooler air

Rainbows can be full circles
Trivia and Stories
Sometimes mist can create double rainbows

A rainbow cannot be physically approached

Mirages sometimes look like puddles to the observer when it is really light being bent from the object
Sound Bites
If you want the rainbow you have to put up with the rain

Try to be a rainbow in someone’s cloud

Sources of Additional Info

Heat Index/Apparent Temperature

Primary Points
Index that combines air temperature and relative humidity

Used to determine the human-perceived equivalent temperature

Also known as the “felt air temperature”

Heat index is assuming shady conditions and light wind

Higher relative humidity keeps the body from evaporating sweat, which cools us

Some people may mistake when the atmosphere is humid or dry

Used to determine how dangerous it is to be outside
Trivia and Stories
Heat index was developed in 1978 by George Winterling

Canada uses a humidex which is similar to the heat index

Heat stroke is imminent when heat index is above 54 Celsius (130 Fahrenheit)
Sound Bites
Don’t blame the heat index for melting your ice cream

It’s not the heat it’s the humidity

Sources of Additional Info

Satellite Imagery/Data

Primary Points
The three main types of satellites images are visible, water vapor, and infrared

Two main types of satellites are geostationary and polar orbiting

Geostationary rotates with the earth

Polar orbiting orbits along lines of longitude passing the poles

Visible images can only be viewed during the night (unless a lot of moonlight Is present)

Infrared can be viewed 24/7

Infrared measures the amount of radiation from cloud tops

Water vapor measures the amount of moisture in the atmosphere

Satellites can also be used to forecast (future Skew-T’s)

Satellites can help predict climate change

Trivia and Stories
The first weather satellite was launched in 1959

The first successful weather satellite was launched in 1960

Visible satellites can use moonlight to see nighttime images
Sound Bites
Meteorologist feast their eyes on satellite imagery to predict future weather

Consider meteorologists to be pilgrims before weather satellites

Sources of Additional Info

Wind Chill

Primary Points
Attempts to quantify how much energy is being lost from bare human skin

Originally Formulated by Antarctic researcher Paul Siple in the 1930s

Siple hung plastic bags of warm water in various temperature/wind combos

New wind chill values were implemented in 2001

New Formula used data from real human skin and modern heat transfer eqns.

New wind chill temps are notably “warmer” than the original values

Useful for general guidelines related to dangers of wind-related heat loss

Shortcomings: does not account for sunshine, humidity, individual health

Shortcomings: confusion with actual air temperatures

Shortcomings: only applies to humans, not animals or automobiles

Trivia and Stories
Siple grew up in Erie, PA, was an eagle scout and ‘frat boy’

Siple coined the term wind chill factor

Siple was opposed to wind chill temperature (wrong units) –“science geek”

Canada now uses the same scale…before 2001 it was different

Sound Bites
New Scale required some people to “freeze their face for science”

Wind chill “allows meteorologist to inflict further pain in bad weather”

Wind chill “further clutters the already cluttered world of weather info”

Slate magazine WIND CHILL BLOWS:

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